Relationship between exposure to air pollutants during pre-pregnancy or early pregnancy and birth defects in Xi'an, 2013-2015: a case crossover study / 中华流行病学杂志

ABSTRACT

Objective To understand the levels of exposure to traffic-related air pollutants including nitrogen dioxide (NO2),PM10 and PM2.5,and the relationship between the exposure to air pollutants during pre-pregnancy or early pregnancy and birth defects.Methods Data on air pollution and birth defects from 2013 to 2015 was collected.A case-crossover design was employed to analyze the exposure-response relationship between traffic-related air pollutants and birth defects.Results A total of 4 235 pregnant women were studied.During the study period,the daily average concentrations of ambient NO2,PM10 and PM25 appeared as 60.83 μg/m3,104.94 μg/m3 and 103.88 μ.tg/m3,respectively,with the concentration of PM2.5 larger than the 2nd version of Standard National Ambient Air Quality Standard.In addition,there were strong correlations seen between each of the pollutants (P＜0.01).After adjustment for the influence of meteorological factors,it was found that the exposure to high level of NO2 and PM10 during pre-pregnancy or early pregnancy increased the risk on birth defects (P＜0.05).Conclusion Levels of exposure to adverse environmental factors during pre-pregnancy or early pregnancy could increase the risk of birth defects,suggesting that in these sensitive periods,women should try to avoid being exposed to high concentration of traffic-related air pollutants as NO2,PM10 etc.in order to reduce the risk of birth defects.